code: def tanh2(x):
      return (np.exp2(2.0 * x) - 1.0) / (np.exp2(2.0 * x) + 1.0)
  
imports: from builtins import zip
  import numpy
  import pprint
  import pytest
  from neon import NervanaObject
  from neon.backends.autodiff import Autodiff
  from utils import allclose_with_out
label_desc: Use image node_id 3 for calling the CustomFunc obj's underlying member method code with example usage: obj.tanh2(x) and returns: unknown